Heterocyclic compounds and cerebral function improvers containing the same as the active ingredient

Abstract

Heterocyclic compound represented by the formula I wherein represents or the like; R 1 represents hydrogen atom, C 1 -C 6 alkyl or benzyloxy; R 2 represents methyl or nil; R 3 represents hydrogen atom, C 1 -C 6 alkyl, C 2 -C 6 alkenyl, C 3 -C 8 cycloalkyl or —CH 2 R 5 [wherein R 5 represents phenyl (which may be substituted with C 1 -C 6 alkyl, halogen atom or cyano)] or thienyl; R 4 represents C 1 -C 6 alkyl, C 2 -C 6 alkenyl, C 3 -C 8 cycloalkyl or —CH 2 R 6 [wherein R 6 represents phenyl (which may be substituted with C 1 -C 6 alkyl, halogen atom or cyano), naphtyl or thienyl]; or R 3 is coupled with R 4 .

1. A heterocyclic compound represented by the formula I: 
       
         
           
           
               
               
           
         
         wherein 
       
       
         
           
           
               
               
           
         
       
       represents 
       
         
           
           
               
               
           
         
         R 1  represents a hydrogen atom, C 1 -C 6  alkyl or benzyloxy; 
         R 2  represents methyl or nil; 
         R 3  represents a hydrogen atom, C 1 -C 6  alkyl, C 2 -C 6  alkenyl, C 3 -C 8  cycloalkyl or —CH 2 R 5  [wherein R 5  represents phenyl (which may be substituted with C 1 -C 6  alkyl, halogen atom or cyano) or thienyl]; 
         R 4  represents C 1 -C 6  alkyl, C 2 -C 6  alkenyl, C 3 -C 8  cycloalkyl or —CH 2 R 6  [wherein R 6  represents phenyl (which may be substituted with C 1 -C 6  alkyl, halogen atom or cyano), naphtyl or thienyl]. 
       
     
     
       2. The compound according to  claim 1 , wherein both R 3  and R 4  are benzyl. 
     
     
       3. The compound according to  claim 1 , which is:
 5,5-dibenzylimidazo[2,1-b]thiazol-6(5H)-one, 
 5,5-dibenzyl-2-methylimidazo[2,1-b]thiazol-6(5H)-one, or 
 5,5-dibenzyl-2,3-dihydroimidazo[2,1-b]thiazol-6(5H)-one. 
 
     
     
       4. The compound according to  claim 1 , wherein
 R 3  represents a hydrogen atom, C 1 -C 6  alkyl, C 2 -C 6  alkenyl, C 3 -C 8  cycloalkyl or —CH 2 R 5  [wherein R 5  represents phenyl (which may be substituted with C 1 -C 6  alkyl, halogen atom or cyano) or thienyl]; 
 R 4  represents C 1 -C 6  alkyl, C 2 -C 6  alkenyl, C 3 -C 8  cycloalkyl or —CH 2 R 6  [wherein R 6  represents phenyl (which may be substituted with C 1 -C 6  alkyl, halogen atom or cyano), naphtyl or thienyl]. 
 
     
     
       5. A pharmaceutical composition comprising:
 at one compound of  claim 1 , and 
 a pharmaceutically acceptable diluent or carrier. 
 
     
     
       6. The pharmaceutical composition of at least one compound of  claim 3  and a pharmaceutical acceptable diluent or carrier. 
     
     
       7. The compound of  claim 1 ,
 wherein 
 
       
         
           
           
               
               
           
         
       
       represents 
       
         
           
           
               
               
           
         
       
     
     
       8. The compound of  claim 1 , 
       wherein 
       
         
           
           
               
               
           
         
       
       represents 
       
         
           
           
               
               
           
         
       
     
     
       9. The compound of  claim 1 , wherein R 1  represents a hydrogen atom. 
     
     
       10. The compound of  claim 1 , wherein R 1  represents a C 1 -C 6  alkyl. 
     
     
       11. The compound of  claim 1 , wherein R 1  represents benzyloxy. 
     
     
       12. The compound according to  claim 7 , wherein both R 3  and R 4  are benzyl.